Chapter 6, page 2 Slide 4 Effect of Sequence on Structure•Sufficient information for folding into correct 3-dimensional structure is in the sequence (primary structure) of the protein•Experiments of Anfinsen and White on Ribonuclease•However—the “folding problem” is one of the major unsolved problems of biochemistry and structural biologySlide 5 Secondary Structure•Folding probably begins with nucleation sites along the peptide chain assuming certain stable secondary structures.•Planarity of the peptide bond restricts the number of conformations of the peptide chain. Rotation is only possible about the•C(alpha)-N bond (the Φ(phi) angle)•C(alpha)-C bond (the Ψ(psi) angle)•See Figure 6.2Slide 6 Steric Constraints on Φand ΨAngles•Examine the effects of rotation about the Φand Ψangles using Kinemage•Download Kinemage•Download Peptide file•Note that some angles are precluded by orbital overlap:•Figure 6.3